Mill roll changing arrangement

ABSTRACT

A quick-replaceable roll assembly for a rolling mill stand, said assembly comprising an inner carriage, rail engaging wheels rotatably mounted on said carriage, means for mounting a lower roll and a pair of bearing structures therefor on said carriage, said means comprising a number of balancing plungers reciprocatably mounted on said carriage and engaging said bearing structures, and means for mounting an upper roll and bearing structures therefor on said assembly in faced engagement with said lower roll.

United States Patent Hlaicsak MILL ROLL CHANGING ARRANGEMENT [75]Inventor: Joseph L. Hlafcsak, Whitehall, Pa.

[73] Assignee: Mesta Machine sburgh, Pa.

[22] Filed: July 7, 1972 [21] Appl. No.: 269,753

Company, Pitt- Related US. Application Data [62] Division of Ser. No.112,336, Feb. 3, 1971, Pat. No.

[52] US. Cl ..72/239 [51] Int. Cl. ..B2lb 31/08 [58] Field of Search..72/238, 239

11 mamas 1 May 22,1973

[56] References Cited UNITED STATES PATENTS 3,638,468 2/1972 Fukui et al..72/239 X 3,665,746 5/1972 Elbe ..72/239 Primary ExaminerMilton S. MehrAttorneyDonn J. Smith [57] ABSTRACT A quick-replaceable roll assemblyfor a rolling mill stand, said assembly comprising an inner carriage,rail engaging wheels rotatably mounted on said carriage, means formounting a lower roll and a pair of bearing structures therefor on saidcarriage, said means comprising a number of balancing plungersreciprocatably mounted on said carriage and engaging said bearingstructures, and means for mounting an upper roll and bearing structurestherefor on said assembly in faced engagement with said lower roll.

12 Claims, 7 Drawing Figures PATENTEL MAY 2 2 973 SHEET 2 OF 4PATENIEDMAY22 ms SHEET H []F 4 MILL ROLL CHANGING ARRANGEMENT Thisapplication is a division of my copending coassigned application of thesame title filed Feb. 3, 1971, Ser. No. 112,336, now US. Pat. No.3,691,809.

The present invention relates to a rolling mill and more particularly toa roll changing rig or similar means to facilitate replacing the workrolls of the one or more mill stands ofthe mill. The invention isespecially useful in conjunction with wide flange and other structuralmills wherein product changes are frequently made, which of coursenecessitate corresponding work roll changes in addition to replacementof worn out work rolls.

Although the invention is described primarily in conjunction withstructural mills and more particularly a wide flange beam mill, it willbe observed that the principles of the invention can be applied toadvantage to other types of mills such as plate, strip, or slabbingmills.

As intimated above, the'operation of most beam and other structuralmills requires frequent product changes and attendant replacement of thework rolls to accommodate the several products of a typical structuralmill. In many cases it is necessary to change the mill rolls asfrequently as eighty to ninety times per month. Of course the number ofchanges will vary from one installation to the next and the numbers ofthese changes, moreover, are dictated primarily by product changesrather than by replacement of worn work rolls. In most structural mills,the work rolls exhibit a long wearing characteristic, as the rollingforces are usually about half of those encountered in a typical coldmill. However, the tolerances of the work rolls in most structural millsare more critical, e.g., to ensure orthogonality of flanges in the caseof a beam mill and in general the straightness of the structuralmembers. These considerations contribute to the frequency of andnecessity of roll changes in a typical structural mill, including butnot limited to a wide flange beam mill of either the dual or singlepurpose variety. It is impossible to minimize the importance ofshortening the mill down time by decreasing the time and labor involvedin the aforementioned relatively large number of roll changes.

Known forms of mill roll changing procedures for this purpose haveconsumed inordinant amounts of time and labor for withdrawing the millrolls from each mill stand and replacing them with a new set of rollseither for product changes or for wear consideration. In consequence,production programs have been unduly lengthened and unit production timehas been unavoidedly increased, particularly for short-run products.Known procedures also have resulted in the use of additional operatingpersonnel, who are not otherwise necessary to the actual operation ofthe mill.

In addition to the physical difficulties involved in handling andtransporting the replacement mill roll, known roll changing procedureshave dictated a rather extensive adjustment or zeroing" program afterthe installation of the replacement rolls and in preparation for achange in products or in product dimensions. Conventionally, afterinstallation of the replacement rolls it is necessary to establish apredetermined reference point with respect to the mill stand and thenewly replaced rolls. In the case of a beam mill both the horizontal andvertical roll assemblies must then be ad justed after the replacementprocedure with respect to the reference point. After the material to berolled has entered the work roll area subsequent adjustment is requiredowing to plastic deformation of the work rolls and associated componentsunder load. This timeconsuming procedure considerably and undesirablyextends the total time involved in replacing the work roll assembly andfurther increases mill down time and attendant loss of production.

These disadvantages of the prior art are overcome in an unexpected andinobvious manner, in accordance with my present invention, by providinga roll change rig or means or arrangement characterized by an ability toremove and replace the mill rolls quickly and with a minimum of labor.The use of roll handling equipment, such as overhead cranes and thelike, is likewise minimized or eliminated altogether at the rolling millsite. In particular the roll change rig is arranged such that assemblyand disassembly of the work rolls can take place in the roll shop orother location remote from the mill stand. Insofar as operation of therolling mill itself is concerned, the mill rolls can be withdrawn andquickly replaced as a unit or complete assembly all of which contributeto a pronounced and unexpected minimization of the mill down time, incontrast to known roll changing procedures. Naturally, the productionallosses intended upon known procedures of roll change are likewiseminimized or largely eliminated.

Of prime importance, and potentially of even greater importance isanother unexpected feature of my invention. This is the capability ofthe replacement roll assembly to be zero-positioned as a unit outside ofthe mill stand. Both the horizontal and vertical rolls (in case of abeam mill) can be adjusted to a definite or predetermined referencepoint, as required. The significant and unobvious character of thisfeature of the invention is readily apparent from the fact that thereplacement roll assembly can be zero-positioned in the roll shop eitherduring or before withdrawal of the previous roll assembly from the millstand. With the capability of zero-positioning the replacement rollassembly externally of the mill stand, the mill obviously can be readiedfor production within a much shorter interval of down time.

Inside the mill stand, the replacement roll assembly can be loweredquickly onto a number of stops permanently mounted in the mill housingin further reduction of replacement time. When the replacement assemblyis thus inserted and seated in the mill housing, the bottom millscrew-ups can be actuated to raise the bottom roll of the assembly intooperating position, and the top roll screw-downs as well as the verticalroll screws can be quickly and efficiently actuated to their newoperating positions.

I accomplish these desirable results by providing a quick-replaceableroll assembly for a rolling mill stand, said assembly comprising aninner carriage, rail engaging wheels rotatably mounted on said carriage,means for mounting a lower roll and a pair of bearing structurestherefor on said carriage, said means comprising a number of balancingplungers reciprocatably mounted on said carriage and engaging saidbearing structures, and means for mounting an upper roll and bearingstructures therefor on said assembly in faceable engagement with saidlower-roll.

I also desirably provide a similar roll assembly wherein said carriageincludes a pair of shelf structures for mounting a pair of vertical rollstructures respectively.

I also desirably provide a similar roll assembly including said millstand having a stationary housing and a movable housing, and means formounting said movable housing for movement longitudinally of saidelevatable rails to accommodate differing lengths of roll assembliedwithin said mill stand.

I also desirably provide a similar roll assembly wherein a side shiftingcar is mounted for movement transversely of an external track section atan interruption therein, said car having a platform substantiallybridging said interruption, a pair of auxiliary tract sections spacedlymounted on said platform, said car being shiftable transversely of saidexternal track section such that each of said auxiliary tract sectionscan be selectively inserted into said external track section at saidinterruption to bridge said interruption, said platform and either ofsaid auxiliary track sections being capable of supporting said rollassembly at a position such that another of said roll assemblies can betransversed along said external track section and the other of saidauxiliary track sections without interrference from the firstmentionedroll assembly.

I am aware of a number of rolling mill arrangements in the generaltechnical area to which my invention pertains, as typified for exampleby the U. S. Pats. to Thompson, No. 3,330,142, Kazebee et al., No.3,367,l62 and Kalberkamp, No. 3,256,728. None of these priorarrangements, however, disclose the features of my invention, eitherwithin the context of my novel roll assembly or the handling meanstherefor. While the Thompson arrangement provides zeroing of controlcircuitry, there is no known arrangement, insofar as I am aware, whichis capable of zeroing a mill roll assembly outside of the mill stand.

During the foregoing discussion, various objects, features andadvantages of the invention have been set forth. These and otherobjects, features and advantages of the invention together withstructural details thereof will be elaborated upon during theforthcoming description of certain presently preferred embodiments ofthe invention and presently preferred methods of practicing the same.

In the accompanying drawings, I have shown certain presently preferredembodiments of the invention and have illustrated certain presentlypreferred methods of practicing the same, wherein:

FIGS. 1 and 1A constitute a composite top plan view, partially insection, of one form of rolling mill stand together with a roll changingarrangement therefor.

FIG. 2 is a side elevational view, partially in section, of theequipment shown in FIG. 2.

FIG. 3 is a front elevational view of the mill stand shown in FIG. 1,partially sectioned, and taken generally along reference line 33 thereofand FIG. 4 is a side elevational view of the roll change rig shown inFIG. 1 and taken along reference line 44 thereof.

FIG. 5 is a partial top plan view, partly in section, similar to FIG. 1and further illustrating a movable housing feature of the invention and,

FIG. 6 is a front elevational view of the apparatus as shown in FIG. 5,with parts in section and other parts broken away to illustrate theinvention more clearly.

Referring now more particularly to FIGS. 1-4 of the drawings, theexemplary form of the invention shown therein comprises a mill stand 10and a roll changing rig denoted generally by the reference character 12.The mill stand 10 in this example includes a pair of housings 14, 16with the housing 16 being mounted for movement along a pair of rails 18.The movable housing 16 thus can be moved to a position relative to thestationary housing 14 as to accommodate a particular length of rollassembly 20 therein. The two housings 14, 16 are stabilized by pairs ofrods 17, 19 which are rigidly secured to one of the housings for examplethe stationary housing 14 and are engaged with the other of the housingsby slideable insertion through aperture means 21. Generally the housings14, 16 are aligned with upper and lower bearing chocks of the rollassembly 20 when in their operating positions. In the particular exampleshown the roll assembly 20 is of minimum length, with the result thatthe upper and lower sections of the housings 14, 16 can be placed inabutting relation as evident from FIG. 2. As also shown in the latterfigure the roll assembly 20 is mounted on an inner carriage 26 providedwith a set of rail engaging wheels 28. The wheels 28 are so spaced andare otherwise shaped to engage elevatable rail sections 30 of the millstand 10, intermediate section 3611, auxiliary rail sections 32 of theside shifting car 34, and the external section 3612.

In the disclosed arrangement of the invention, the roll assembly 20 isshaped for closely fitted insertion through a window 38 of each of themill stand housings 14, 16, as better shown in FIG. 3. The roll assembly20 in this case is configured for rolling wide flange beams and the likeand includes upper and lower horizontal rolls 4t}, 42 and vertical rolls44, 46, all of which are mounted, as presently described on the innercarriage 26 to form with the carriage 26 the unitary roll assembly 20.In furtherance of this purpose, the upper horizontal roll bearing chocks48, are nested onto the vertical roll housings 52, 54 respectively, eachof which are troughed at 56 for this purpose. Each of the vertical rollhousings S2, 54 is provided with spacers 58 to aid in aligning the upperhorizontal roll chocks 48, 50. Each of the vertical roll housings 52, 54in turn is slidably mounted respectively on shelf structure 53 or of theinner carriage 26 in contrast to previous practices of mounting thevertical rolls directly on the mill housings. Each lower horizontal rollbearing chock 60 or 62 is provided with means such as the spacers 64 foraligning the vertical rolls 44, 46. In furtherance of this purpose eachvertical roll housing 52, 54 is provided with a pair of downwardextensions 66 each of which is notched at 68 for engagement withpositioning plungers 70 which are mounted in theinner carriage 26 asshown. The plungers 70 and extensions 66 therefor stabilize and positionthe vertical roll housings 52, 54 on the roll assembly 20 andparticularly with respect to the upper and lower rolls 40, 42.

Similarily the inner carriage 26 is provided with pairs of plungers 72for similarily elevating and balancing the lower horizontal roll 42. Theplungers 72 can be hydraulically actuated if desired, and the plungerscan be fitted into suitable bores or cylinders for that purpose.

Roll necks 74, 76 of the upper and lower horizontal rolls 40, 42respectively protrude through the associated bearing chocks forengagement by suitable drive spindle couplings (not shown). The verticalrolls 44, 46 are not necessarily driven in this application.

The inner side of the inner carriage 26 is provided with a number ofstop surfaces 78 at which the inner carriage is brought to rest on pairsof stops 80 permanently secured to the sill structure 82 of each housingwindow 38 as better shown in FIG. 3. The stop surfaces 78 and stops 80are engaged when the mill stand rail sections 30 are lowered, forexample by actuation of cylinder arrangements 84. At this time the rollassembly including the inner carriage 26 is stationarily and rigidlysupported on the pairs of housings stops 80. However, before operationof the mill stand is commenced, it is in accord with another unexpectedfeature of my invention that the inner carriage 26 is completelyunloaded as far as the roll assembly 20 is concerned, and the lower roll42 of the latter is supported directly by the mill housings 14, 16. Thisis accomplished by supporting the roll assembly, in particular the lowerhorizontal roll 42 thereof, directly by the mill stand screw-ups 86.

In furtherance of this purpose each screw-up 86 is threaded through thebottom of each mill housing 14 or 16 and extends into bearing engagementwith the associated lower horizontal roll chock 60 or 62 through anaperture 88 therefor in the adjacent end of the inner carriage 26 (FIGS.2 and 3). Thus, when the roll assembly 20 has been properly installedwithin the mill housings 14, 16 by convenient use of the inner carriage26, the roll assembly 20 then can be engaged directly by the mill standin the usual manner. For this purpose each vertical roll housing 52 or54 is provided with a pair of inclined stop surfaces 90 for engagementrespectively by a pair of clamping plungers 92 carried in the associatedmill housings 14 or 16.

The position of inner carriage 26 within the mill stand is secured by apair of lower clamp plates 94 mounted on the movable housing 16 adjacentthe window 38 thereof to properly contain the roll assembly 20 in themill stand 10. Similar and cooperating upper clamp plates 96 can bemounted in like manner on the movable housing 16 adjacent the window 38for the same purpose.

The upper horizontal roll 40 can be positioned for adjusting thehorizontal roll gap by means of screwdowns 100 mounted in the uppersections of the mill housings 14, 16. Likewise, hold-down forces alsoare applied to the work roll chocks 38, 50 of the upper horizontal roll40 by means of the same screwdowns 100.

As noted previously the elevatable housing rails 30 are aligned with theintermediate track section 36a which is interrupted at 37, and with thejuxtaposed pair of the auxiliary track segments 32a or 32b of the sideshifting car 34 depending on the position thereof, and with the externaltrack section 36b. The external track section 36b can extend to a rollshop (not shown) or to suitable warehousing facilities for the rollassemblies located remotely or the rolling mill.

The use of the side shifting car 34 affords a temporary holding area fora replacement roll assembly 20a to permit withdrawal of the used rollassembly 20 (FIG. 1) without interference between the withdrawn andreplacement roll assemblies.

The side shifting car 34 provided in accordance with this feature of theinvention, includes a platform 102 supported on axles 104 and railwaytrucks 106. The car 34 is movable along a relatively short length oftrack including rails 108. Mounted on the platform 102 are the pairs ofrails 32a, 32b mentioned previously. These rails are spaced sufficientlyto permit passage of the roll assemblies 20, 20a or other forms of rollassemblies,

the widths of which are limited by the housing windows 38. The width ofthe car platform 102 provides rail segments 32a, 32b of sufficientlength to accommodate the longest roll assembly that can be incorporatedinto the side shifting mill housing structure 14, 16. An example of suchroll structure is denoted at 20b in FIGS. 5 and 6 of the drawings. FIGS.5 and 6 also show the rods 17, 19 in the expanded position and theincreased separation of the mill stand housings 14, 16 to incorporatethe longer roll assemblies 20b.

The platform 102, including the rails 32a, 32b which can be recessedtherein as shown in FIG. 4, is mounted on a base structure 103 for addedstrength, which in turn is mobilized by the axles 104 and railway trucks106.

As better shown in FIGS. 1 and 4, slideable metal plates 110, 112 can bejoined respectively to the end portions of the car platform 102 to coverthe well 114 or recess in which the side shifting car 34 isreciprocated. The sliding plates 110, 112 thus provide coverage for thecar well 114 irrespective of the position of the side shifting car 34. Apersonnel hazard is thereby eliminated.

The carrying out of the roll-changing procedure will now be described.Prior to withdrawal of the used roll assembly 20 (FIG. 1), thereplacement roll assembly 20a is brought from the roll shop or from asuitable storage area along the external track section 36b. Suitabletraction means (not shown) can be employed to propel the replacementroll assembly 20a along the external track section 36b. Before thereplacement roll assembly 20a reaches the side shifting car 34, thelatter is reciprocated to the left of its position as shown in FIG. 1,such that its auxiliary track section rail segments 32b are aligned withthe external track section 36b. The replacement roll assembly 20a isthen pushed onto the side shifting car 34 and the latter is moved to theright to the position thereof as shown in FIG. 1. This places thereplacement roll assembly 20a in the position as shown in FIG. 1 so thatthe used roll assembly 20 when withdrawn, can be wheeled directly to theroll shop or other location by means of the elevatable mill rails 30,the intermediate track section 36a, the side shifting car rail segments32a, the external track section 36b, all of which are then alignedtherewith as illustrated in FIG. 1. One of the unexpected results of theinvention, in addition to the use of the side shifting car 34, is thatseparate carriage means do not have to be supplied for each of the rollassemblies 20, 20a, as this function is provided by the inner carriage26 which forms part of each roll assembly 20 or 20a in accordance withthe invention.

Owing to the unitary character of the roll assembly 20 or 20a orequivalent assembly made in accordance with the invention, the rollassembly can be leveled and zeroed externally of the mill stand 10. Thiscan be accomplished either in the roll shop or on the side shifting .car34 when the replacement roll 20a is located thereon as shown (FIG. 1).The obvious advantage of this feature of this invention is theaccomplishment of such leveling and/or zeroing or other adjustment ofthe replacement roll assembly 20a prior to shutting down the rollingmill including the mill stand 10, with the admirable result that milldown time is drastically reduced.

In the case of the wide flange beam roll assembly 20a a typical rollleveling and zeroing procedure in accordance with the invention will nowbe described, as it falls into the general category of mill rollreplacement procedure. Initially suitable hydraulic lines (not shown) orother source of motive power are coupled to the replacement rollassembly 20a in order to actuate the various hydraulic plungersdescribed previously. The lower horizontal roll 42 is then raised bymeans of plungers 72 to the normal pass line (not shown) of the millstand 10, with the assumption that the replacement roll assembly 200 issupported externally at its elevation in the mill stand 10, irrespectiveof whether the assembly is supported on the side shifting car 34 or onthe external track section 36b at the roll shop. At this position thelower roll 42 is faced against the upper horizontal roll 40. Thevertical roll housings 52, 54 are now moved toward the horizontal rolls40, 42 by means of plungers 70 until the center-line surfaces of thevertical rolls 44, 46 just touch the sides of both horizontal rolls,which vertically aligns the sides or end surfaces of the horizontalrolls. The verticalroll housings are consequently aligned by means ofspacers 64 positioned in the lower horizontal roll chocks 60, 62 suchthat the center lines of the vertical rolls 44, 46 are aligned with theinterface 41 of the engaged upper and lower horizontal rolls 40, 42 at apredetermined material pass line 116. The upper horizontal roll 40likewise can be aligned as necessary by means of spacers 58 positionedin the vertical roll housings.

The horizontal and vertical rolls 40-46 are now zeroed with one anotherand the replacement roll assembly 20a is ready for traversing into themill stand 10. The aforedescribed zeroing is preserved owing to theunitary character of the mill roll assemblies, as described previously.

After the replacement roll assembly 20a is thus readied for insertioninto the mill stand 10, the mill is then shut down preparatory towithdrawing the used roll assembly 20. The upper horizontal roll balance(bracket 98) is deactivated to permit the upper horizontal roll 40 againto face and rest on the lower horizontal roll 42. The vertical rollscrews 24 are then retracted to their outward limits. The carriageassembly clamp plates 94 and the upper horizontal roll clamp plates 96are opened in order to permit the roll assembly 20 to be raised to itsroll change position by raising the mill stand rails 30 by cylinders 84to a position of alignment with the intermediate tract section 36a. Thebottom screw-ups 86 are then retracted to clear the inner roll assemblycarriage 26.

After raising the spindle carriers (not shown) to support the drivespindles (not shown) which are withdrawn from the horizontal roll necks74, 76 on the drive side, the used roll assembly 20 is withdrawn throughthe mill stand windows 38 by suitable traction means (not shown) acrossthe mill rails 30, the intermediate tract section 360 and onto the sideshifting car 34.

The side shifting car 34 is then actuated by suitable traction means(not shown) to the position thereof as shown in FIG. 1 to remove theused roll assembly 20 from its position in front of the mill stand tothe position denoted by replacement roll assembly a of FIG. 1. The usedroll assembly 20 is now removed from in front of the mill stand 10preparatory to insertion of the replacement roll assembly 20a into themill along the intermediate track section 36a.

As an initial step in the re-insertion precedure, the drive spindles(not shown) are adjusted radially, if required, to receive thereplacement roll assembly 2642. At the same time the drive spindles areraised to receive the roll necks 74, 76 of the replacement roll assembly20a. The replacement roll assembly 20a including its inner carriage 26is then traversed into the mill stand 10 where it is positioned withinhousing windows 38. The clamp plates 94 and 96 are closed, thus properlycontaining the replacement roll assembly 20a within the mill stand. Thespindle carriers are then re tracted, whereupon the elevatable millstand rails are lowered to permit the replacement roll assembly 20a torest on the mill housing stops 80. The housing screw-downs 100 are thenlowered to engage the upper horizontal roll chocks 48, 50, after whichthe screw downs 100 are leveled for proper alignment of the replacementroll assembly 20a. The bottom screw-ups 86 at this time are raised forinsertion through the inner carriage 26 into engagement with the lowerhorizontal roll chocks 60, 62 respectively. After leveling the screw-ups86, the bottom lift cylinders or plungers 72 of the inner carriage 26are retracted from the lower roll chocks 60, 62. The vertical rollscrews 24 of each mill housing 14 or 16 are run in to touch the verticalroll housings 52, 54 and then leveled. The vertical roll positioningcylinders or plungers are deactivated followed by energization of thevertical roll balance cylinders. The upper horizontal roll balancebracket 98 is then engaged to complete the installation procedure.

Prior to insertion into the mill stand, the replacement roll assembly20a can be prepared in the roll shop. The inner carriage 26 is placed onthe external track section 36b. The thickness of the spacers 64 isestablished in proportion to the roll radius of the lower horizontalroll 42 in order to face the roll on a pass line of the roll assembly20a which can thereafter be aligned to coincide with the material passline 116 of the mill stand. The vertical roll assemblies including theirhousings-52, 54 are then added to the roll assembly 20a as shown inFIGS. 2 and 4, with the vertical roll housings engaging the spacers 64and the vertical roll adjusting cylinders 70. The upper horizontal rollspacers 58 are likewise adjusted in proportion to the roll radius of theupper horizontal roll 40 such that the roll is faced approximatelyagainst the lower horizontal roll 42 at the vertical roll pass line 116.The roll assembly is then transferred to the side shifting car 34 asoutlined above.

After the replacement roll assembly 2611 is zeroes as described aboveexternally of the mill stands 14, 16 the assembly is inserted into themill stand through the housing windows 38. With all the rolls at thezero position and with the roll assembly aligned such that its pass linecoincides with a predetermined material pass line 116 of the mill stand,the entire roll assembly 26a is preloaded or prestressed within the millstand by means of the horizontal and vertical screws to establish apositive reference at the zero position. This is made possible byapplying sufficient preloading forces to subject the roll assembly tothe anticipated elastic deformations encountered during the rollingoperation. The preload force therefore should be at least equal to themaximum anticipated rolling force. The preload forces are then relievedand the mill controls are operated to back off the vertical andhorizontal rolls to openings therebetween which are less than therolling dimensions by predetermined values. The roll openings then areexpanded to the precise rolling dimensions by insertion of a work piece.

From the foregoing it will be apparent that novel and efficient forms ofa Mill Roll Changing Arrangement have been described herein. While Ihave shown and described certain presently preferred embodiments of theinvention and have illustrated presently preferred methods of practicingthe same it is to be distinctly understood that the invention is notlimited thereto but may be otherwise variously embodied and practicedwithin the spirit and scope of the invention.

I claim:

1. A quick-replaceable roll assembly for a rolling mill stand, saidassembly comprising an inner carriage, rail engaging wheels rotatablymounted on said carriage, means for mounting a lower roll and a pair ofbearing structures therefor on said carriage, said means comprising anumber of balancing plungers reciprocatably mounted on said carriage andengaging said bearing structures, and means for mounting an upper rolland bearing structures therefor on said assembly in faceable engagementwith said lower roll.

2. The combination according to claim 1 wherein said assembly includes apair of vertical roll structures and said upper and lower rolls arehorizontal rolls, means are provided for mounting said vertical rollstructures on said carriage, and the bearing structures of said upperroll are mounted on said vertical roll structures respectively.

3. The combination according to claim 2 wherein said carriage includes apair of shelf structures for mounting said vertical roll structuresrespectively.

4. The combination according to claim 2 wherein balancing means areprovided on each of said vertical roll structures for engagement withsaid upper roll bearing structures respectively.

5. The combination according to claim 2 wherein adjustment and balancingplungers are mounted on said carriage structure for engagement with eachof said vertical roll structures.

6. The combination according to claim 1 wherein said inner carriage isprovided with a number of apertures shaped for passage of screw-upsnormally provided in said mill stand, said apertures being positionedfor alignment with said screw-ups respectively when said assembly isproperly located within said mill stand.

7. The combination according to claim 1 wherein said mill stand includesa number of rigid stop members engageable with said carriage forsupporting said assembly including said carriage, said mill stand alsoincluding a pair of elevatable rails engageable by said carriage, andmeans for aligning said rails with an external track section and forlowering said rails to a position out of engagement with said carriageso that said assembly including said carriage rests entirely upon saidstop members.

8. The combination according to claim 7 wherein a side shifting car ismounted for movement transversely of said external track section at aninterruption therein, said car having a platform substantially bridgingsaid interruption, a pair of auxiliary tract sections spacedly mountedon said platform, said car being shiftable transversely of said externaltrack section such that each of said auxiliary track sections can beselectively inserted into said external track section at saidinterruption to bridge said interruption, said platform and either ofsaid auxiliary track sections being capable of supporting said rollassembly at a position such that another of said roll assemblies can betraversed along said external track section and the other of saidauxiliary track sections without interference from the firstmentionedroll assembly.

9. The combination according to claim 8 wherein said side shifting caris wheel-mounted on a pair of rail members extending transversely ofsaid external track section.

10. The combination according to claim 1 including said mill standhaving a stationary housing and a movable housing, and means formounting said movable housing for movement longidutinally of saidelevatable rails to accommodate differing lengths of roll assemblieswithin said mill stand.

11. The combination according to claim 2 wherein means are provided forslidably mounting said vertical roll structures for movement intobearing contact or engagement with horizontal rolls for alignment ofhorizontal rolls.

12. The combination according to claim 2 wherein means are provided forelevating each of said vertical roll structures relative to apredetermined faced engagement between horizontal rolls for alignment ofsaid vertical roll structures therewith.

1. A quick-replaceable roll assembly for a rolling mill stand, saidassembly comprising an inner carriage, rail engaging wheels rotatablymounted on said carriage, means for mounting a lower roll and a pair ofbearing structures therefor on said carriage, said means comprising anumber of balancing plungers reciprocatably mounted on said carriage andengaging said bearing structures, and means for mounting an upper rolland bearing structures therefor on said assembly in faceable engagementwith said lower roll.
 2. The combination according to claim 1 whereinsaid assembly includes a pair of vertical roll structures and said upperand lower rolls are horizontal rolls, means are provided for mountingsaid vertical roll structures on said carriage, and the bearingstructures of said upper roll are mounted on said vertical rollstructures respectively.
 3. The combination according to claim 2 whereinsaid carriage includes a pair of shelf structures for mounting saidvertical roll structures respectively.
 4. The combination according toclaim 2 wherein balancing means are provided on each of said verticalroll structures for engagement with said upper roll bearing structuresrespectively.
 5. The combination according to claim 2 wherein adjustmentand balancing plungers are mounted on said carriage structure forengagement with each of said vertical roll structures.
 6. Thecombination according to claim 1 wherein said inner carriage is providedwith a number of apertures shaped for passage of screw-ups normallyprovided in said mill stand, said apertures being positioned foralignment with said screw-ups respectively when said assembly isproperly located within said mill stand.
 7. The combination according toclaim 1 wherein said mill stand includes a number of rigid stop membersengageable with said carriage for supporting said assembly includingsaid carriage, said mill stand also including a pair of elevatable railsengageable by said carriage, and means for aligning said rails with anexternal track section and for lowering said rails to a pOsition out ofengagement with said carriage so that said assembly including saidcarriage rests entirely upon said stop members.
 8. The combinationaccording to claim 7 wherein a side shifting car is mounted for movementtransversely of said external track section at an interruption therein,said car having a platform substantially bridging said interruption, apair of auxiliary tract sections spacedly mounted on said platform, saidcar being shiftable transversely of said external track section suchthat each of said auxiliary track sections can be selectively insertedinto said external track section at said interruption to bridge saidinterruption, said platform and either of said auxiliary track sectionsbeing capable of supporting said roll assembly at a position such thatanother of said roll assemblies can be traversed along said externaltrack section and the other of said auxiliary track sections withoutinterference from the first-mentioned roll assembly.
 9. The combinationaccording to claim 8 wherein said side shifting car is wheel-mounted ona pair of rail members extending transversely of said external tracksection.
 10. The combination according to claim 1 including said millstand having a stationary housing and a movable housing, and means formounting said movable housing for movement longidutinally of saidelevatable rails to accommodate differing lengths of roll assemblieswithin said mill stand.
 11. The combination according to claim 2 whereinmeans are provided for slidably mounting said vertical roll structuresfor movement into bearing contact or engagement with horizontal rollsfor alignment of horizontal rolls.
 12. The combination according toclaim 2 wherein means are provided for elevating each of said verticalroll structures relative to a predetermined faced engagement betweenhorizontal rolls for alignment of said vertical roll structurestherewith.